First of all, what is pronunciation? Most people would say it's a part of 'accent,' and that intonation would be the other part of accent.
I think teachers may focus on vocabulary and grammar rather than on pronunciation because they think that of these three, the latter is the least important part of improved communication skills. In many ways, they may be right about that.
But early pronunciation instruction is also important, for the following reasons:
1) improved pronunciation shows that students have become more native-like in their categorical perception of sounds. This means that they are more likely not only to sound like natives when they speak, but also to understand which sounds are in words that natives to them (i.e., improved listening comprehension). In addition, they are more likely to have improved phonetic spelling skills, and improved abilities to correctly sound out new words they read. Thus, more native-like speech sounds can lead to better listening skills, reading skills, and spelling skills.
2) pronunciation is generally much easier to learn at an early age. The longer a teacher ignores the subject, the less his/her students will ever be able to learn about it. Thus, ignoring pronunciation skills until grammar and vocabulary have improved will often mean ignoring pronunciation altogether.
3) ignoring pronunciation means that for the most part, students will always have a foreign sounding accent. Granted, understanding what students mean to communicate is much more important than the accent they use when communicating. However, the unfortunate fact is that when laypeople (non-language educators) listen to someone with a foreign accent speak, they tend to focus on HOW the message is expressed as much or even more than on WHAT is expressed. Communication suffers, because of the accent and the listeners' perceptions/prejudices about it. Studies have shown that, especially in the U.S. business world, professionals tend to judge unknown speakers with foreign accents to be less intelligent (!) than unknown speakers with local accents. Is this an insane situation? Yes. Is it a reality your students will face? Sadly, yes.
My own policy is to include about 20 minutes of pronunciation practice in every hour-long ESL session, and then refer back to the sounds we studied whenever they come up in new words, etc.
You decide which sounds to work on first. The 'short' vowel sounds (short because that's what we call them, not because they necessarily have to be said quickly) are often the most useful sounds to work on for reading and spelling improvement. Short vowels are the vowel sounds in these words: bat, bet, bit, bought, butt. However, they're also some of the most difficult to teach, because the tongue just hangs in the middle of the oral cavity without any easy reference points to touch. Sometimes front consonant sounds ( like /f, v, th, b, p, m/ or even /s, t, l, n, z, d/ are better to start with, so students can see what your tongue is doing.
Hope this helps. Feel free to email me if you need any ideas.
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